Which type of malware is specifically designed to lock and deny access to files until a ransom is paid?

Ransomware is a type of malware that encrypts a user's files or locks them, making those files inaccessible until a ransom is paid to the attacker. This malicious software typically displays a message demanding payment for the decryption key or for restoring access to the system. The primary motive behind ransomware attacks is financial gain, and they can cause significant disruption and financial loss to individuals and organizations.

In contrast, other types of malware serve different purposes. Spyware secretly monitors user activity and collects information without the user's consent. Worms are designed to replicate and spread across networks, often without needing a host, while adware displays unwanted advertisements on a user's device, typically generating revenue for the creator but usually not directly harming the user’s data. Each type of malware has its specific characteristics and objectives, but ransomware is distinct in its focus on extorting money through file access denial.